1. Field of the Invention
The present invention relates to systems and methods for inspecting integrated electronic components, and particularly for inspecting ball grid array (BGA) connected components.
2. Description of the Related Art
Electronic circuit packaging technology presents an important aspect of circuit design. Improved methods of packaging offer improvements in circuit performance as well as cost and time savings. Since its development in the 1960""s surface mount technologies, in which electronic components are soldered directly to metal pads on the surface of a printed circuit board, have supplanted conventional xe2x80x9cthrough-holexe2x80x9d packaging methods. Such technologies afford better circuit performance and a higher connection density. Some of the currently available surface mount technologies are the plastic-leaded chip carrier, the small-outline integrated circuit, chip capacitor, chip resistor, ball grid array, and chip scale package.
As with any packaging technology, efficient methods and systems for the inspection and verification of the component connection quality are important to implementing surface mount technologies. X-ray inspection is sometimes used to verify component connections, particularly those where some of the connections are obscured for an ordinary visual inspection.
Ball grid array technology generally employs a dense grid of discrete solder balls to facilitate electrical connection of an electronic component (such as a application specific integrated circuit (ASIC)) and a printed circuit board (PCB). With precision alignment and heating, connection is made between an array of solder pads on the component and another corresponding array of solder pads on the printed circuit via the melted solder balls. The advantages of BGA packaging include reduced component size, cost, and weight, higher I/O count for a given substrate area, improved electrical performance and an easy extension to multi-chip modules. Because the grid presents obscured connections, X-ray inspection is commonly used to verify the integrity of BGA connections.
Furthermore, many component designs employing surface mount technology, and particularly BGA technology, have symmetrical connection patterns of solder pad arrays. These symmetrical connection patterns are preferred (in fact, standard) because they provide a dense arrangement of connections and convenient processing. A dense pattern of connection is a principle motivation for surface mount technologies, including BGA technology. Proper orientation of the component with symmetric connection patterns is conventionally determined by a visual indicator when the component is integrated with the printed circuit board. However, improper orientation of the component still occurs.
Visual orientation indicators are typically silk screened onto the exterior of the component, invisible to an x-ray inspection. In some cases physical features built into the housing material of the electronic component are also used as markers to indicate proper orientation of the electronic component. However, the housing material is always invisible to x-rays; an x-ray visible housing material would prevent any x-ray inspection of the electronic component integration. Thus, connection integrity inspection and orientation verification are currently performed as two separate processes.
There is a need for more efficient systems and methods of inspection for electronic circuit packaging. There is a need for additional inspection checks with a minimum of additional equipment and procedures. There is particularly a need for such improved systems and methods for inspecting component orientation of BGA packaging. There is further a need for such systems and methods without sacrificing the benefits of symmetrical connection patterns. The present invention meets these needs.
The present invention discloses a method and apparatus providing inspection of the orientation of an electronic component integration where x-ray inspection is employed to verify the connection integrity of the electronic component after integration. Thus, the invention is particularly useful for surface mount technologies, such as a ball grid array (BGA) integration. The present invention can be incorporated into existing integration inspection processes requiring a minimum of additional time and equipment.
An exemplary method of producing inspectable electronic components using the invention comprises providing an electronic component for integration and providing an x-ray visible orientation indicator for the electronic component such that proper orientation of the electronic component is verifiable by x-ray inspection after integration of the electronic component. The x-ray inspection also makes connection integrity of the electronic component verifiable after integration of the electronic component.
An exemplary method of inspecting electronic components using the invention comprises producing an x-ray of an electronic component after the electronic component is integrated, wherein the electronic component includes an x-ray visible orientation indicator and performing x-ray inspection of the x-ray to verify connection integrity of the electronic component and to verify proper orientation of the electronic component.
An exemplary apparatus using the invention, comprises an electronic component for integration and an x-ray visible orientation indicator for the electronic component such that proper orientation of the electronic component is verifiable by x-ray inspection after integration of the electronic component. The x-ray inspection also makes connection integrity of the electronic component verifiable after integration of the electronic component.
The invention can be used with any x-ray inspected integration technology, such as surface mount technologies like ball grid array integration. The invention is useful where the electronic component includes a symmetrical arrangement of solder pads and/or solder balls.
In one embodiment, an x-ray visible orientation indicator has metal content. The x-ray visible orientation indicator can be produced as part of a manufacturing process of the electronic component. For example, the x-ray visible orientation indicator can be produced as part of fabricating a die for the electronic component (e.g. the orientation indicator is fabricated in the die), silk screening markings on the electronic component (e.g. one mark being the orientation indicator), or producing solder pads for the electronic component (e.g. a unique solder pad being the orientation indicator).